Add PDF Reader

Adds PDF reading capability to all container agents using poppler-utils (pdftotext/pdfinfo). PDFs sent as WhatsApp attachments are auto-downloaded to the group workspace.

Phase 1: Pre-flight

1. Check if container/skills/pdf-reader/pdf-reader exists — skip to Phase 3 if already applied
2. Confirm WhatsApp is installed first (skill/whatsapp merged). This skill modifies WhatsApp channel files.

Phase 2: Apply Code Changes

Ensure WhatsApp fork remote

git remote -v

If whatsapp is missing, add it: